I would highly recommend that instead of making this a web app, you turn it into a theme of some sort. Most people will not want ANOTHER profile on ANOTHER domain. But, many people do still want to have their own domain.
Make it easy for me to direct my dns at you, and then it makes more sense for me as a user.
Make it easy for me to direct my dns at you, and then it makes more sense for me as a user.